Wilhelm Dengler

Anxiety in patients with an automatic implantable cardioverter defibrillator: what differentiates them from panic patients?

OBJECTIVE Anxiety seems to be a frequent problem in patients with an automatic implantable cardioverter defibrillator (AICD). Distressing experiences before or after AICD implantation such as resuscitation, or AICD shocks are suspected as causes for enhanced anxiety levels. A closer examination of the level and structure of anxiety in AICD patients and a comparison with panic patients might help to examine additionally both conditioning and cognitive models of anxiety. METHODS There were 61 AICD patients examined with a specifically designed AICD questionnaire and standardized anxiety and depression questionnaires. Subgroups of AICD patients without, with some, and with definite anxiety related to AICD shocks were compared with panic patients and healthy control subjects. RESULTS Although fear of dying was greatly reduced by AICD implantation, approximately one third of the AICD patients, especially patients with definite anxiety related to AICD shocks, were characterized both by enhanced anxiety levels and avoidance behavior. These patients were comparable with panic patients in most questionnaire scores. Anxiety levels were not associated with objective AICD shock experiences or medical variables. CONCLUSIONS Anxiety in AICD patients seems to be unrelated to traumatic experiences, a finding that casts doubt on pure conditioning models of anxiety. Presumably, a life-threatening cardiac disorder increases the likelihood for catastrophic interpretations of bodily signs, especially in anxiety prone AICD patients. In accordance with cognitive models of panic disorder, this cognitive dysfunction could lead to anxiety and depression levels comparable with those of panic patients.

A priori expectancy bias in patients with panic disorder

BACKGROUND Several studies have indicated that phobic participants tend to overassociate fear-relevant stimuli and aversive outcomes, i.e, they show a covariation bias. Such a bias seems to be a powerful way to confirm danger expectations and enhance fear. Therefore, a covariation bias might be an important factor in the maintenance of fear. METHODS To investigate a covariation bias in patients with panic disorder, we had 29 patients and 29 healthy control participants rate the a priori probabilities with which they would expect pictures of mushrooms, spiders, erotic scenes, and emergency situations to be paired with a tone, shock, or nothing. RESULTS This is the first study to show that patients with panic disorder specifically overestimate the association between panic-relevant stimuli and a following negative consequence. This distorted contingency expectancy represents a panic-specific covariation bias, since it was not observable for other stimuli-consequence combinations and only to a significantly lesser degree in control participants. CONCLUSIONS The underpinning hypothesis is that overestimation of threat plays a casual role in the origins and maintenance of anxiety. Thus anxiety may induce a covariation bias, which in turn may enhance the perceived threat, which in turn may intensify the anxiety etc. This reciprocal relationship between covariation bias and anxiety may have clinical implications for prediction and treatment in patients with panic disorder.

Selective processing of pain-related word stimuli in subclinical depression as indicated by event-related brain potentials.

An intense discussion still exists as to whether pain and depression are causally related or independent of each other. To investigate processing of pain-related word stimuli in subclinically depressed individuals, we designed an event-related potentials study in a group control design. Pain words and neutral words were presented to 16 subclinically depressed and 16 control participants. Behavioral and electrophysiological measures were taken during lexical decision and recognition tasks. Depressive compared to control participants showed enhanced P300 amplitudes at parietal electrodes triggered by pain-related words during the lexical decision task, which presumably is a sign of enhanced recollection processes for these word stimuli. In line with these electrophysiological findings, depressed participants also tended to better recall the pain-related words in the later recognition task than control participants. We conclude that subclinically depressed individuals selectively process pain-related stimuli, and this processing bias could enhance their vulnerability to develop pain symptoms.

Fixation suppression of the vestibulo-ocular reflex (VOR) during sinusoidal stimulation in humans as related to the performance of the pursuit system

Fixation suppression (FS) of the vestibulo-ocular reflex (VOR) was tested during passive sinusoidal body rotation with a frequency of 0.1 to 1.0 Hz and stimulus amplitudes ranging from 10 degrees to 240 degrees. To test whether FS can be explained by an internal pursuit signal opposite to the VOR, pursuit and the VOR under different instructional sets were studied. Both pursuit and FS decrease with increasing frequency and stimulus amplitude and seem to be limited by stimulus acceleration. Gains in FS calculated on the basis of the VOR during mental arithmetic correspond closely to the frequency and amplitude dependent pursuit gain, suggesting that an internal pursuit signal plays a major role in VOR suppression.

A priori expectancy bias and its relation to shock experience and anxiety: a naturalistic study in patients with an automatic implantable cardioverter defibrillator.

Patients with an automatic implantable cardioverter defibrillator (AICD) may offer an unique naturalistic opportunity to study whether expectancy biases develop because of precipitating aversive or traumatic experiences and/or because of elevated anxiety. An expectancy bias and its associations with AICD discharge and anxiety was examined in 24 AICD patients with a thought experiment. While patients without AICD discharge exhibited no expectancy bias, patients with discharge experiences were found to expect that stimuli depicting medical emergency situations will be followed by an aversive consequence. The magnitude of their expectancy bias was positively correlated with their anxiety level. In the group with AICD discharge, patients with low anxiety levels exhibited no bias, while patients with high anxiety levels exhibited a rather strong bias. It seems that the experience of an aversive or traumatic event, here an AICD discharge, is a necessary (but not sufficient) precipitating event for the development of an expectancy bias. If such an event happens, trait anxiety level presumably determines if and how strong the expectancy bias will be.

Implantable cardioverter defibrillator shocks are prospective predictors of anxiety

OBJECTIVES To examine the temporal contingency of anxiety and implantable cardioverter defibrillator (ICD) therapy (anti-tachycardia-pacing and shocks to prevent ventricular tachycardia and/or fibrillation). BACKGROUND It is under debate whether anxiety is a precursor and/or consequence of ICD-therapy. METHODS In a prospective longitudinal study, fifty-four patients undergoing first-time ICD-implantation were assessed for anxiety, frequency of ICD-shocks and anti-tachycardia-pacing up to two days before ICD-implantation (T0) and twelve months later (T1). RESULTS Anxiety at T0 did not predict frequency of ICD-shocks at T1, but ICD-shocks significantly predicted increased anxiety at T1. In contrast, anxiety at T0 and T1 was unrelated to frequency of anti-tachycardia-pacing. Effects remained stable when we controlled for potentially confounding variables (e.g. age, sex, cardiac health and depression at T0). CONCLUSION Our findings indicate that repeated ICD-shocks are a cause of anxiety in ICD-patients rather than a consequence, thus shock frequency should be minimized.

Decreased duration and altered topography of electroencephalographic microstates in patients with panic disorder.

The topography and temporal sequence of scalp electrical fields were analyzed by adaptive segmentation of the continuous electroencephalogram (EEG) in 27 patients with panic disorder and 28 control subjects during rest phases and during the viewing of a neutral (mushroom) or an emotionally relevant (casualty) picture. The results indicate decreased duration of brain microstates in panic patients during all conditions. Comparison of the resting phases with the viewing conditions revealed a significant acceleration of EEG microstates in both the patients and the control subjects. Patients and control subjects differed in the topography of the fields during rest: control subjects showed a left-anterior/right-posterior orientation, while panic patients showed a predominantly right-anterior/left-posterior orientation. Neither group displayed any topographic changes when viewing the mushroom picture. However, when viewing the anxiety-specific casualty picture, panic patients shifted fields in a different way than did control subjects. Centroid topography does not permit clear localization of the cortical generators. It is concluded that panic patients show a generally increased cortical activation compared with healthy control subjects, and activate different neuronal arrays when viewing an anxiety-specific stimulus.

Pursuit Opposite to the Vestibulo-ocular Reflex (VOR) during Sinusoidal Stimulation in Humans

Pursuit opposite to a simultaneously activated vestibulo-ocular reflex (VOR) was tested during passive sinusoidal body oscillations (0.1-1.0 Hz, amplitudes 10-80 degrees) about the vertical axis in 4 healthy humans, while subjects were asked to pursue a small target moving in phase with the rotating chair with about half its amplitude relative to the head and 1.5 times its amplitude with respect to space. The decrease in gain of the pursuit opposite to the VOR occurred at lower stimulus frequency, stimulus velocity and stimulus acceleration than pure visual pursuit when gain was calculated in relation to target motion in head coordinates. It resembles that of pure pursuit when calculated in relation to target motion in space (earth coordinates, sum of the displacements of the mirror image and of the chair) thus taking the oppositely directed VOR into account. The data fit the assumption of a linear interaction of the VOR (in counterphase) and pursuit.